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iMac turns off suddenly

Hello!


Since upgrading to Lion I have had my iMac 3 times tunr off right in the middle of working. Different apps all the time. It never has done this using snow leopard. Just started after I upgraded to Lion. Is there anywhere in the console to look at logs to see what is happening or is anyone else haveing a similiar issue?


Thanks!!!

Posted on Jul 22, 2011 8:20 PM

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22 replies

Jul 25, 2011 4:07 PM in response to TempusThales

After further digging, and a bit more time in the forums, it seems that there is an issue with Lion and some discrete graphics cards. IF you set your Mac to ONLY use the integrated graphics (using a tool such as gfxcardstatus, or the built in preferences on the older MBP), then you may find relief until Apple puts out an update.

Aug 13, 2011 12:19 AM in response to TempusThales

Have you guys tried resetting the PRAM?


Shut down your computer

Unplug all of the periffirals and the power cords

Leave unplugegd for 30 seconds and plug back in

When starting up, hold down Option+Command+P+R until the screen goes black

When the computer reboots let go of the keys


It seemd to have solved my issue momentarilly but im digging around for more information online

Sep 7, 2011 9:32 AM in response to TempusThales

Same for me (1 year old 27" iMac). Never done this before & has been randomly shutting down for weeks now. It started out very bad - every few minutes in the days immediately after I installed Lion, now it's about 1-2 times per day (or less). I also have a Macbook Pro that has no problems at all.

I have spent hours on the phone with Apple - tried every test & nothing has solved the issue.

They suggested it could be old incompatible software, so I have basically stripped my mac of any software I no longer use (and now there is nothing on the iMac that isn't in the laptop). I used Appcleaner to make sure all component parts of old software was removed.


I also use Cocktail to complete a complete system maintence daily (repair permissions + clean out caches etc).


Between those two actions, the computer is at least usable now, but its certainly not fixed.

iMac turns off suddenly

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